The 4S doesn't render the iPhone 4 obsolete, and on the surface they're nearly identical. But with a faster processor, new software, a voice-activated personal assistant and a souped-up camera, it's a major improvement.
The 4S went on sale with the price range depending on storage space. If you're sporting an older model such as the 3GS or considering making the leap to an iPhone from another type of handset, it's an excellent excuse to buy one.
The coolest new feature on the 4S is Siri, a software-based personal assistant who responds to your voice in a somewhat robotic, yet soothing female tone.
Siri can set your alarm clock, find a good local sushi joint and play DJ with your music. Once you let her know who you are and where you live, she can remind you to call your boyfriend when you get home. She can understand conversational English, which means you can say things like, "What's happening today?" or "What's going on today?," and she'll let you know what's on your calendar.
She's also a dictation dynamo, transcribing e-mails and texts much better than a phone running Google Inc.'s Android software. Beyond Siri, I was happy to see a better camera on the 4S, which has an 8-megapixel lens compared with 5 megapixels on the iPhone 4. The new camera can also take pictures faster, and pictures shot in dim lighting look better.
You can even record high-definition videos in 1080p on the 4S -- the best resolution currently available on a consumer camera.
The iPhone 4S has the latest version of Apple's mobile software, iOS 5, which seems geared toward making the phone even easier to use.
One of the best additions to iOS 5 is iMessage, which lets you send texts, photos or videos to other Apple devices. That makes it easier to send texts to iPads and other devices that aren't phones. It also saves you texts, if you're not on an unlimited text plan. The iPhone 4S's performance is noticeably bumped up by a new dual-core A5 chip, which is the same processor in the latest iPad. With this chip, the phone can process graphics and complete other tasks much faster. Web pages, especially graphics-heavy ones, loaded faster than they do on the iPhone 4.
Call quality was decent over Verizon Wireless' network, though it sounded a bit flat. Calls are supposed to be improved on the 4S with the inclusion of two antennas that the phone can use to receive or send data.